Telephone-exchange system



, 1909 2 sheets-sheet 1 B. D. WILLIS TELEPHONE EXCHANGE SYSTEM Aug. 24 1926.

Filed Nov. 29

D EE Patented Aug. 24, 1926.

UNITED- STATES PATENT OFFICE.

BERNARD D. WILLIS. OF CHICAGO, ILLINOIS. ASSIGNOR, BY MESNE ASSIGNMENTS, T0

AUTOMATIC ELECTRIC INC.` OF CHICAGO. ILLINOIS, A CORPORATION OF DELA- WARE.

TELEPHONE-EXCHANGE SYSTEM.

Application filed November 29. 1909. Serial No. 530,399.

My invention relates to telephone systems in general, but more particularly to automatic or semi-automatic telephone exchange systems of that particular type in which selectors and connectors are employed. and more especially to systems of this kind in which no operating grounds are employed at the substations, and in which the electric current for talking purposes is supplied to the lines from one or more batteries at the exchange or central station.

Generally stated the object of my invention is the provision of an improved sys* tem wherein the actuating or propelling r magnets of certain switches, such. for example, las the second selectors and connectors, are controlled by the relay or relays of the first selector, rather than by relays which are individual to the said second selector-s and connectors.

A special object of my invention is the provision of a system of this kind in which the current for talking purposes is supplied to the calling line through the first selector and to the called line through the connector-that is to say, a system in which there are bridging coils in the first selectors for supplying` talking current to the calling lines. and in which there are bridging coils in the connectors for feeding talking current to the called lines.

Another object is the provision of a system of this kind in which the relay or relays of the first selector control the other switches, such as the second selector and the connector, when the call is from one line to another line in the same exchange, so that no relays are necessary for the connectors that are required for giving service between subscribers of the same exchange, but in which connectors with line relays are employed for extending calls from one exchange to the other, whereby connectors without relays are available for local calls; and connectors having line relays are available for service between the two exchanges, or between a main exchange and a subexchange, in which case the connectors with relays would be located at the subexchange.

Another object of my invention is the provision of a system of this kind in which the first selectors are controlled over metallic circuits, and in which the relays of the first selectors are capable of controlling the other switches. such as the second selectors and the connectors, over grounded line circuits, as by grounding first one side and then the other of a trunk line, which is a distinguishing feature of what is commonly known as a three-wire system.

To the foregoing and other useful ends my invention consists in matters hereinafter set forth and claimed.

ln the accompanying drawings Figures 1 and Q are a diagram of the circuits and apparatus for connecting a calling subscriber A of a first exchange with a called subscriber A of a second exchange in a system embodying the principles of my invention.

ln Fig. 1 the line of the calling subscriber terminates in the line switch C belonging to a group controlled by the master sWitchAD. As sliowinthe calling line has been extended through the first selector E and through the second selector F.

Fig. 2 is a similar view representing circuits and apparatus of the second exchange, and showing a continuation of the circuit from the second selector (Fig. 1) through the connector H and the line switch C to the called subscriber A. The switch C is similar to the switch C, and the substation A of the second exchange is also similar to the substation A. v

.At I (Fig. 2) is shown a ringer generator, at J a busy-signaling machine, at K a ringer interrupter and at B a battery with its positive terminal preferably grounded at G. Itwill be noted that the battery lead 80 is common to both exchanges. This is not necessary, however, as another battery might be provided in Figs. 1 and 3 with its positive terminal preferably grounded, and the common connecting battery lead 80 might then be omitted.

Fig. 3 is a diagrammatic representation of a connector similar to the connector H located, however, at the first exchange, and is used for making local calls in that exchange,

prises a receiver 2, induction coil 3, trans- -mitter 4, switch hook 5, ringer 6, and an imofthe line switch disclosed in British Patent No. 26,301of 1906, and similar to that described .inthe American Telephone Journal of Chicago ,.lllinois, of June, 1908.

In its general form it ,comprises a trip mag.

net 1.17, arelease magnet26 and a bridgeeut-off relayk 27. The tripl magnet 'is designed to operate the usual plunger for pressing the banksprings :18 and 19, 20 and 21, 22 and 23 and 24 yand 25 (of which there are a number of similar sets) into engagement. This plunger is so arranged that when in normalfposition it is under ,the control of the masterswitch D, whereby the said plunger may always be removed from opposite a seized trunk to a position opposite an idle trunk. The release magnet operates to restore the plunger to normal position. The brid, i;ecutoi:` relay 27 operates to shift l the springs 74 and 77 out of engagement with the springs 7 3 and 78, respectively.

The master switch D may be of any suitable or approved type, for instance of the general type. described and illustrated in the saidAmerican Telephone Journal of Chicago, Illinois, of'June 6, 1908. Its bank O comprises the individual segments a (one for each set of line switch bank springs) and the common segment34. The master switch controls the plungers of several line switches, usually one hundred, holding them always in readiness to engage an idle trunk terminal. This particular master switch shaft is given a step-by-step reciprocating motion, and all idle plungers .are held in locking engagement with said shaft. The plungers of the line switches 'are Vnot self-aligning--that is, a plunger does not automatically come into locked engagement with the shaft until the master switch shaft again resumes the original position where the plunger was tripped. )Vhen one line switch operates, itsplunger is tripped and engages the springs of the bank terminals of an idle trunk. The motor magnet relay 31 is accordingly energized.

This relay 'operates to close the motor magnet circuit and the circuit of the relay 33. The motor magnet operates to rotate the ratchet wheel and fibre interrupt-er wheel. When the ratchet wheelis operated one notch the interrupter wheel has rotated enough to close the springs 91 and 92, which keep the mot-or magnet operating until the idle plungers are directly opposite the bank terminals 4of an idle trunk. When this position 1s reached the springs 91 and 92 separate, and as the master switch wiper 35 has been moved to a position on the master switch bank corresponding to the idle trunk, the motor magnet is deenergizcd. )Vhile the motor magnet is operating the relay 33 is. energized, thereby shitting the. spring 79 out of engagement with the spring 81 and into engagement with the spring 92. In this way all the trip magnets are disconnected from the battery lead and connected to a busysignaling current similar to the busy-signaling current furnished by the apparatus in. F ig. 2, thus preventing the selection of a busy trunk and giving a subscriber the busy signal if all the trunks are busy.

The first selector E is of the general type disclosed in United States Letters Patent to Keith, Erickson and Erickson, No. 815,321, granted March 13. 1906, but modified to operate in. conjunction with a two-wire system. One of the improved features of this selector over the usual first selector of this type, used in the said two-wire system, is that the. operations of the succeeding switches in a connection are controlled by relays of the switch E. The first selector switch E embodies the following devices: The wipers 36, 37 and 38 which are secured to ashaft (not shown) which has a vertical motion controlledl by the vertical magnet 39 and a. rotary motion controlled by the rotary magnet 40. The side switch, comprising the wipers 41, 42, 43 and 44. is controlled by the private magnet 45. The operation of the switch is under the control of the subscriber through the medium of the relays 46, 47 and 48. A release magnet 49 is provided for restoring the switch to its normal position when the calling subscriber hangs up his receiver.

The second selector F is of the general type as the irst selector E, but'has no line relays. It is operated b the subscriber through the medium of t e relays ofthe iirst selector switch E. The switch F, as here shown, comprises the usual shaft wipers 50, 51 and 52, side switch comprising the wipers 53, 54, 55 and 56, vertical magnet 57, rotary magnet 58, private magnet 59, release magnet 60 and release relay 61. The connector H is of the general type disclosed in United States Letters Patent No. 815,176, granted March 13, 1906, to Keith, Erickson and Erickson; but, like the second selector F, is adapted for two-wire work and is operated through' the medium of the relays of the first selector E. After the connection has been extended from the calling substation through the selector switches E and F to the connector H, impulses from said substation are repeated by the relay 46 (Fig. 1)

t0 the relay 62 (Fig. 2). Each time the reenergize lay 62 energizes, while the side switch is in first osition, the vertical magnet 63 1s d to raise the shaft. of the connector H, together' with the wipers 64, 65 and 66, one step. Then the side switch is in second position the energization of relay 62 results in energizing the rotary magnet 67 to step the shaft and its wipers around. The relay 68 is operated through the medium of the relay 48 of the selector switch E, the relay 68 in turn controlling the operation of the private magnet 69 whichgoverns the side switch. The doublewwound relay 70A energizes when the called subscriber answers and operates to open the circuit of the ringer relay 71 and to energize the relay 7 2 which locks and maintains the circuit of the ringer relay open until the connector H isv released, thus preventing the bell of the' called substation from being rung when the subscriber at that substation hangs up his receiver before the receiver at the calling substation is restored to the switch hook. As soon as the 'connector H completes con# nection with the desired line the ringer relay 71 begins to be intermit-tenly` energized through the medium ofthe interrupter K. This continues until the called subscriber answers, when the circuit of ringer `relay is opened as above mentioned. When the ringer relay is energized it opens the line connection and bridges the ringer generator I across that portion of the line leading to the called substation.

In order to give a clear understanding of,

the operation of the system I will now explain how the subscriber at substation A may operate the exchange switches to obtain a connection with the substation A,'

whose number will be assumed to be 2220. When the receiver is removed from the switch hook at substation A (#5000) an energizing circuit isclosed through the trip magnet 17 of the line switch C, causing the said magnet to attract its armature and allow the plunger to be thrust into a bank of contacts containing the terminals of a trunk leading to a first selector E; The energizing circuit for the trip magnet 17 extends from ground G through springs 78 and 77, line conductor 14, switch hook springs 76 and 75, impulse springs 10 and 9, primary winding 15 of induction coil 3, transmitter 4, line conductor 13, springs 74 and 73, trip magnet 17, springs 79 and 81 to the battery lead 80, thence through hat tery B to ground Gr. 'Vhen the line switch plunger is thrust into the bank the springs 18 and 19, 20,and 21, 22 and 23 and 24 and 25 are pressed into Contact in pairs, as indicated. The engagement of springs 24 and 25 furnishes a guarding potential from ground G2 to the normal eopductor 82 for protecting the line of substation A against seizure. The engagement of springs 24 and 25 also furnishes an energizing cir- 'cutting off the ground G and trip magnet 17 from the line conductors 13 and 14. The

energizing circuit of the relay 27 extends from ground G2 through springs 24 and 25 and relay 27 to the battery lead 80, thence through battery B to ground G. The engagement of springs 22 and 23 closes a circuit extending ;trom ground Gr3 through the motor magnet relay 31 of the master switch D to the common segment 34, thence over wiper 35 to contact 83 upon which it is assumed the wiper 35 is at this time resting, thence over conductor 84 and through springs 23 and 22 and magnet 26 to battery lead 80. Upon the closure of this'circuit the relay 31 operates to force the springs 85 and 86 into engagement, but the release magnet 26 does not energize because its resistance is low comparedv with' that of the relay 31. The closure of springs 85 and 86 energizes theV motor magnet 32 in multiple with the relay 33 over a circuit extending from ground at the points Gr4 and i 80,',thence through the battery B to ground G. The' motor magnet 32 attracts its armature 89, which' brings'the pawl 90 into engagement with the ratchet wheel 29, thereby moving it one step. Vhen the said'ratchet wheel is moved one step the spring 91, which rests normally at the bottom of a tooth of the wheel 30, is forced upward and into engagement with the spring 92, whereby the circuit through the motor magnet 32 is maintained, regardless of the Springs 85 and 86. The-motor magnet 32, being provided with the interrupter springs, now continues to operate like a buzzer to rotate the ratchet wheel 29 and the toothed wheel 30 until the spring 91 drops down into the next notch. By this time the plunger shaft will have advanced all the plungers -which, are in locked engagement with it to the nexttrunk` and the wiper 35 willvhave left the contact' 83, allowing-the relay 31 to-deenergize and motor magnet .o stop. A'alf the next trunk is busy, however, the wiper 35 will find al ting ofi the liatterylead from all the trip magnets of all the line switches to which the master switchD. 1s allotted. This is provided so that no line switch may he operated while its plunger is being moved hy the master switch. The spring 202 of the relay 33 is connected with a busy-signaling machine so that any subscriber who tries to make. a call while his master switch is operating will receive the busy signal.

As soon as the connection is extended from the line conductors 13 and 14 to the selector` E thrcugh "the s}.irings 18 and 19 and 20 and 21, the relay 46 is energized. The energizingcircuit for the relay 46 extends from ground G through the' winding 93 of vsaid relay, through springs 21 and'20 v to the line conductor 14, thence through substation A, line conductor 13, springs 18 and ,19 and winding 204 of the relay 46 to the batteryl lead. The relay 46 uponenergizing ,shifts the spring 96 out of contact with the u. spring 94 jand into contact with thespring`v 19T, whereby the slow-,acting relays 47and 48 are energized. .The energizing circuit of the relay 47 extends fromground Gf. through the ing removes aground from the release mag- 35. net 49. and connects the impulse'spring .109

'l tical 1nagnetf39.. .In its energized condition -the relay 48 maintains the circuit through A ythe switch E open at points between the springs 103 and 104 and v105 and 106. The engagement of the springs 107 and 103 closes a circuit from ground G through the springs 107 and'103, side switch wiper. 41

infirst position, contact 108 and private` magnet 45` to the battery lead 80, whereby the private magnet is energized preparatory to releasingr the side switch to second position. The switch E is now in position for S receiving impulses for the first digit of the number to be called.l

As vthe dial at substation A returns to normal after being operated for the rst digit (2),the impulse teeth 8 separate the springs 9 and 10 twice, allowing the relay 46 to deenergize a like number of times. .lila-ich time the relay 46 deenergizes, the springs 109 and 95 close a circuit through the vertical magnet 39, while the circuit through the relay 47 is opened between the springs 96 and 9T. The relay 47, however, is slow-acting and does not have time to deenergize while the springs 96 and 97 are separated. Each time the. springs 95 and 109 engage, the vertical magnet is energized over a circuit extending from ground Gr26 through springs 95 and 109. springs 100 and 101, conductor 113, side switch wiper 412, contact 11:2, vertical magnet 39 to the batter) lead, thence through battery B to ground The vertical inagnct is energized twice over this circuit and operates to raise the shaft wipers 36, 37 and 38 two steps to a pointl opposite the second bank level. As soon as the switch shaft is raised the iist step the circuit formerly traced through relay 48 is broken at a point between contact point 99 vand spring 98, but said relay 48 receives an energizing impulse each time 'and relay 46 deenergizes through springs 96 and 94 and contact 114, which is now in engagement with the spring 98. The relay 48 being slow-acting does not allow its armature to` restore to normal between impulses.. As soon as the impulses cease, however, the relay 46 resumes its energized position, and the circuit through the relay 48 is permanently' opened bythe separation ot'springs 96 and 94. The relay 48 now ,has time to deenergize .and open the circuit of the private magnet 45 at .a point .between the springs 107 and 103.

j'lhe private magnetthereupon deenergizes and allows the side' switch to pass to second position, the wipers'engaging their secondposition contact-points. -When the side l.switch ,wipers 41 and l42 leave their contact -pointsofv the first ,position they break the 'connection normallyexisting between the private magnet 45 andconductor 115, and

` Vbetween/the .vertical magnet 39 and conducthrough the springs 100 and 1 01 to thejvertor 116.jfThe side switch wiper 44, in its second position, closes a circuit from ground G1.1 -through the rotary magnet and interrupter springs 117 to the battery lead 80, thence through battery B to ground G. The rotary magnet if thereupon energizes and rotates the shaft wipers one step onto the terminals of the first trunk of the. second level. It this trunk is not busy the side switch will be immediately tripped to third position by the action of the rotary armature; but if the first trunk is busy the private wiper 38 will find the first contact grounded. When the private wiper engages the contact of. a guarded trunk the prlvate magnet is energized over a c'ircuit extending from said grounded contact through side switch wiper 43, private inagnet 45 to the battery lead 80. The private f tion A through the shaft wipers 36 and 37 to the second selector F. 'When the wiper 43 engages the third-position contact a guarding potential is supplied from ground Y 12 to the'private wiper 38, thence to the corresponding private bank contacts `of all the first selectors having access to the second selector F. The side switch wiper43, in third position, also closes an energizing circuit from ground G12 through said wiper 43, shaft wiper' 38 and release relay 61. The relay 61 upon energizing separates the springs 118 and 119, thereby maintaining the circuit of the release magnet 60 open, which would otherwise be closed as soon as the switch shaft is raised one step and spring 120 permitted to engage With con-A tact point 121.

Now when the dial at substation A is operated for the second digit (2) the relay 46 is deenergized twice, as before, but the switch F is now'under the control of said relay 46`and is operated to extend the con nection through to a connector H. Each time the relay 46 deenergizes a circuit is closed from ground G26 through springs 95 and 109, springs 100 and 101, side switch wiper 42, shaft wiper 37 side switch wiper 54 of the switch F and vertical magnet 57 to battery lead 80. The vertical magnet is energized twice over thiscircuit, and operates to raise the shaft and shaft Wipers 50, 51 and 52 .two steps. Each time the relay 46 deenergizes an energizing circuit is alsoy closed through the relay 48. This circuit extends from ground G8 through said relay 48, spring 98, contact point 114 and springs 94 and 96 to battery lead 80, thence through battery B to ground G. The relay 48 energizes upon the first impulse andl remains energized until all the impulses are completed. In this case, however, the engagement of springs 107 and 103 closes an energizing circuit for the private magnet 590i the second elector F. This circuit extends from ground G10 through springs 107 and 103, conductor .115, side switch wiper 41,

' shaft wiper 36, side switch wiper 53 and private magnet 59 to the battery lead 80, thence through battery B to ground G. After the impulses cease, and relay 48 again has time to deenergize, the circuit'through the private magnet 59 is opened and the side switch of the second selector released t0 second position. l/Vith the side switch in second position the wiper 56 closes an energizing circuit from ground G15 through the rotary magnet 58 to the battery B, said circuit including the interrupter springs 122. As soon as this circuit is closed the rotary magnet operates once to -rotate the shaft wipers onto the contacts of the first trunk of the second bank level, opposite which the Said wipers were placed by the vertical magvswitch F tothe shaft B' torground G.

net. If this trunk is'busy, however, the prian idle trunk, whereupon the private magnet deenergizes and releases the side switch to third position. As soon as the side switch wiper 56 leaves the second-position contact the energizing circuit of the rotary magnet is broken. The wipers 53 and 54, in third position, extend the connection through the wipers 50 and 51, thence over conductors 123 yand 124 to connector H. The side switch wiper 55, in third position, supplies guarding potential sov from ground G1e to private wiper 52, thence to all the private bank contacts of the seized trunk in order to protect it against seizure by any other second selector. The side switch wiper 55, in third position,.also closes an 4energizing circuit for the release relay 179 of' the connector H. This circuit extends from ground G1, side switch wiper55, shaft wiper 52, conductor 191 and relay 179 to battery lead 80, thence through battery The lay 179 upon energizing separates springs 180 and 181 t0 maintain the circuit of the release magnet- 182 open after the shaft permits the spring 184 to engage t-he tcontact point 183.

The connection having been extended to the second or sub-exchange the connector H is now in a position to respond to the impulses for the last two digits ofthe called number and extend the connection through to the line of substation A (#2220) When the dial at substation A (#5000) is operated for the third digit (2) the relay 46 is deenergized twice, as for the previous digits. Each time the relay is deenergized for this digit the engagement of springs 109 and 95 furnishes an energizing circuit for the relay 62 of lthe connector H. This energizing circuit extends from ground G26 through springs and 109, springs 100 and 101, side switch wiper 42, shaft wiper 37, side rswitch Wiper 54, shaft wiper 51, trunk conductor 124, relayv 62, side switch wiper 148, to the battery lead 80,thence through battery B to ground G. Each time this circuit is closed the relay 62 forces springs 127 and 128 into contact, thereby closing an energizing circuit for the vertical magnet 63. This circuit extends from ground G18 through side switch wiper 125, contact point 129, springs 127 and 128, vertical magnet 63, contact vpoint 132, side switch 'wiper 133.f

the first impulse and remains in an oper-- ated position until all impulsesV are delivered. When the ,relay l48 energizes for the third digit it closes an energizing circuit for the relay 68 of the connector H, said` circuit .extending from ground G1 through springs'v 107 an 103, vconductor Y115, side switch wiper 41, shaft wiper 36, side switch wiper 53, shaft wiper 50, conductor 123,

side switch wiper 134, relay 68 to the battery lead 80, thence through battery B to ground G. Relay 68 thereupon energizes to close an energizing circuit from ground G." throughV springs 136 and 135, and through the private magnet 69 to the batf tery lead 80, thencethrough; battery B to ground G. After the impulses cease the relay 48 deenergizes to open the circuit of relay 68, which in turn deenergivzes to open the circuit of theA private magnet 69. The deenergization of the private magnet allows the side switch to move into second position. When the side switch reaches second position the wiper 133 places the'rotary magnet 67 under the control of the relay 62. When the dial at substation A is 'operated for the fourth -digit (0) the relay-62 responds to the im ulses in the same manner as when the thir digit (2)' was called, but in this case the engagement of springs 127 and'128 closes an energizing circuit for the' rotary magnet 67. This circuit extends from ground G, side switch wiper 125, contactv 130, springs 127 and 128, rotary magnet 67, contact 137 and side switch wiper 133 to batte lead 80. The rotary magnet is energize' 4t'en times 'over this circuit and operates to rotate the switch shaft to carry the wipers ontothe terminals of the desired line #2220. In this case, as before, the rivate magnet 69 is energized upon the rst impulse from the substation A, and

. if the called line is not busy the private magnet deenergizes4 after the impulses are completed and the side switch is permitted to move into third osition, thus completing the connection to t e called line. If, however, the called line is busy the private wiper 66 finds the private contacto line #2220 grounded, sald ground being supplied by some other occupying connector similar to H or if ,the substation #2220 'has made a call this4 -ground is supplied by the line switch C. rIn either case, when the private wiper rests on this grounded contact an en ergizing circuit is established extending from said grounded contact through wiper 66, side switch wiper 153 (bearing in mind that the sideswitch is still in second position), and through the private magnet 69- to battery lead 80, thence through battery B to ground G. The private magnet is maintained energized over this .circuit and the side switch locked in second position after vswitches F and E, through substation apparatus and back through switches E and F, through relay 62 to the battery lead 80. The

.calling subscriber will continue to receivethe busy-signal over this circuit until lie hangs up his receiver, thus releasing the connection, or until the guarding potential is removed from the private bank contacts,

when the side switch will be released to third position and the connection thus completed. If the line #2220 had not been busy when called, the side switch would have been released tothird position immediatel after the impulses for the last digit (0 were completed. Whenthe side switch wiper 134 -reaches third position the trunk conductor 123 is cut through to a spring of relay 70. When 'the side switch wiper 153 reaches third position it establishes an energizing circuit for the bridge-cut-oir` relay 192 of the line switch C. This circuit extends from ground G20 through side switch wiper 153, shaft private wiper 66, andthrougli the relay 192 to the battery lead 80, thence through the battery B to ground G. The

relay 192, upon energizing, operates to disconnect ground from the line conductor 156,

and the trip magnet of line switch C from the conductor 157, so as not to interfere -'with the talking battery circuit of substation A.

The side switch wiper 148, in third position, completes a connection from the battery lead 80 through the springs149 and 150 and 152 and 151 to the ringer relayf( 1, whereby the ringer relay is intermittently energized through the medium of the. interrupter niachine K. The action of this interrupter will be'explained later. When the ringer relay 71 energizes it shifts the springs 143 and 146 out of engagement with the springs 144 and 147, respectively, and into engagement with springs 142 and 145. By this action connection is broken between springs 146 and 147, and between 143 and 144, and the ringer generator I is bridged across that portion of the line leading to substation A. The ringer 193 now receives ringing current over a circuit extending from one side i of generator I through springs 142 and 143,

shaftwiper 64, conductor 157, ringer 193, condenser 194, hook switch springs 195 and 196, conductor 156, ringer relay springs 146 and 145 and back to the other side of the generator I. When the subscriber at substation A removes the receiver from the hook, the spring 196 is shifted out of engagement with spring 195 and into engagement with spring 197, whereby the transmitter 198 and primary winding of .the induction coil 199 are bridged across the line conductors 156 and 157 in place of the ringer 193 and condenser 194. When this is done the substation A is supplied with talking battery current the iiist time the ringer relay 71 is deenergized thereafter.

It is understood, of course, that .the ringer'l relay 71 is energized intermittently and that the receiver at substation A might be rev moved from the hook at a time when the ringer relay is energized and the battery potential iscut 'ofi'. The circuit for the talking current of 'substation A extends from ground G1? through side switch wiper 125, winding 154 of relay 70, ringer relay springs 147 and 146, shaft wiper 65, line conductor 156, springs 196 and 197, impulse springs 200, primary winding of the induction coil 199, transmitter 198, line conductor 157, shaft wiper 64, ringer relay springs 143 and 144, winding 155 of relay`70 and through side switch wiper 133 to the battery lead 80, thence through the battery B to ground G. The relay energizes upon the closure of this circuit and operates to close contact between springs 158 and 159, 158EL and 159a and 160 and 149, and to open the contact between springs 149 and 150. The engagement of springs 158 and 159 an-d 158a and 159 eX- tends the conductors 123 and 124 through to the called line. The disengagement of springs 149 and 150 removes the battery connection from the ringer relay 71, so that it cannot be energized again after the called subscriber answers. The engagement of springs 160 and 149 closes an energizing circuit extending from ground G21 through relay 72, springs 160 and 149- and side switch wiper 148 to battery lead 80. Upon the closure of this circuit the relay 72 energizes and locks. The locking circuit extends from ground G21 through relay 72, springs 161 Iand 162 and side switch wiper .133 tol bat-- tery lead80, thencethrough battery B to ground G. In its energized position the relay 72 opens the battery connection of the ringer relay .7l at a second point by the separation of springs 151 and 152. The relay 72 will remain locked in its energized position until the switch H is released, opening the circuit of relay 72 at the side switch.

. Y wiper 133. With this arrangement it will be seen that after the called subscriber has once answered, his bell will not be rung again after the receiver is hung up even though the calling subscriber does wait some time before restoring his receiver to the switch hook.

I will now explain the action of the interrupter K, by means of which the ringing is made intermittent. The relay 163 is provided with two windings` 164 and 165. lVinding 164 has a high resistance while the resistance of winding 165 is comparatively low. The ringer relay is so wound that it will operatively energize ywhen included in a circuit in series with the two windings 164 and 165 connected in multiple, but when the relay 71 is connected in 'series with winding 164 alone said relay 71 will not energize, but relay 163 will attract its armature. Now when the side switch of the connector H first passes .to third position the circuit through the hinger relay extends from ground G22 through winding 164 of relay 163, thence through ringer relay 71 and springs 152 andlland 150 and 149 and side switch wiper 148 to battery. The

relay 163 energizes upon 'closure of this circuit. When the relay 163 energizes it operates to close contact between springs 168 and 169, whereby an energizing circuit is closed through the motor magnet 170. This circuit' extends from ground G23 through motor magnet 170, interrupter springs 171 and 172 and springs 168 and 169, thence through battery B to ground G. The motor magnet upon energizing attracts its ar-',

mature 173, which forces the pawl174 into engagement with the ratchet wheel 17 5, rotating it one step. When .the armature 173 reaches the bottom of its stroke the interrupter springs 171 and 172 are separated, the magnet 170 deenergizes, the armature 173 restores to normal, closing the interrupter springs again, and consequently themagnet 170 is again energized and the ratchet wheel 175 rotated another step. The motor magnet will continue to operate in this manner to give the ratchet wheel 175 a continuous rotary motion as long as the relay 163 remains energized. As the ratchet wheel 17 5"v revolves, the toothed wheel 176 is carried around with it. When the tooth, 177 passes from under spring 167 this spring makes contact with spring 166, thus closing the circuit through winding 165. 'The ringer relay, now receiving current through the windings 164 and 165 in multiple, energizes i and bridgesthe ringer generator I across the line of substation A', s before eXplaned. Each time a tooth of the wheel176 passes the spring 167 the circuit through/the winding 165 is opened and the ringer relay is deenergized. When the receiver at substation A is removed from the hook and the batthrough the springs 96 and 94. As soon as- -A is hung up the energizing circuit of the relay 46 1s broken at a point between the springs 75 and 76. The relay 46 deenergizes and opens the circuit of relay 47 at a pointbetween'springs 96 and 97, and also connects the release magnet 49 with the battery B relay 47 deenergizes two circuits are closed, one through the release magnet "49 of the first selector E and one through the release magnet 26 of the line switch C in series with the relay 17 8. The circuit through the release magnet 49 extends from ground Gr9 through springs 102 and 103, release magnet 49, normal spring 98, contact point 114 and springs 94 and l96 to the battery lead 80, thence through battery B to ground G. The magnet 49 upon energizing restores the selector to normalposition, andthe. circuit of the magnet 49 is opened at a point between spring 98 and contact 114 when the switch shaft reaches its normal position, and the contact will be closed between spring 98 and contact point 99. The other circuit closed by the deenergization of relays 46 and 47 extends. froml ground G9 through springs 102 and 103, relay 17 8, springs 110 and 111, bank contacts 23 and 22, release magnetv 26 to battery lead 80, thencey through battery B to ground G. The magnet 26 and relay 178, which are included in this circuit, energize. The relay 26 upon energizingv attracts its armature andholds it in readiness to release the switch C. When the relay 178 energizes, the springs 179 and 180 are pressed into engagement and a circuit is closed through the relay 47, thereby again energizing this relay. This circuit extends from ground G7 through relay 47, contact point 99, spring 98 and springs 180:l and 179" to battery lead 80, thence through battery B to ground Gr. )Vhen the relay 47 ener izes it separates the springs102 and 103, t ereby breaking the circuit through the relay 178 and release magnet 26, as well as its own circuit. Since the relay 47 is slow-acting ,it maintains the circuit open long enough for the release magnet 26 to deenergize and release the line switch C. The separation of the bank s rings 22 and 23 upon the withdrawal of t e line switch plunger maintains the circuit of the relay 17 8 open after the relay 47 returns to normal posltion. When the side switch wiper 43 leaves the third position upon the release of the first 'selector E, it

initiates the release ofthe second selector F in the following manner: When the side switch wiper 43 leaves its grounded third-` position contact the circuit of the release te lay 61 of the second selector F is opened. The relay 61 thereupon deenergizes, permitting the spring 118 to engage the spring 119, thereby closing the circuit of the release magnet 60e This circuit extends from ground G" through the release magnet 60, springs 118 and 119, contact point 121, normal spring 120 to the battery lead 80, thence through battery B to ground G. The magnet 60 energizes and releases the switch F. )When the switch shaft reaches its normal position it forces the spring 120 out of engagement with the contact point 121, thereby opening the energizincr circuit of the reilease. magnet 60.

p The release of the second selector F in turn brings about the release of the connector H by opening the energizing circuit of the release relay 179 at the side switch wiper .55 and shaft wiper 52. The relay 179 upon deenergizing permits the springs 180 and 181 to engage,'thereby closingthe energizing circuit of the release magn-ct 182. which energizes to release the connector H.- The energizing circuit of the release magnet 182 extends from ground Gr24 through the magnet 182, springs 180 and 181, contact` point 183 and normal spring 184 to the battery lead 80. It is broken ,when the switch shaft returns to normal osition, thereby separating the sprinvr 184 rom the contact point 183. The locking circuit of the relay 72 is broken as soon as the side switch wiper 133 leaves the third position upon the release of the connector H. i

From the foregoing it is evident how a subscriber at substation A in one exchange may obtain connection with a subscriber of a distant exchange. It has been assumed here that the trunks from the second level ioo of the second selector banks lead to connectors H located at a distant exchange, while the trunks from the first level of the second selectors lead to connectors (Fig. 3) located in the same exchange as the selectors E and F (Fig. 1). If the subscriber at substation A had called #2120 (not shown) instead of #2220, the operation of the selectors E and F would have been the same as previously described, yexcept that the second selector Wipers would have been raised only one ste and have selected a trunk in the first ban level leading to a connector similar to that shown in Fig. 3. When the calling device at the substation A is operated for thel sec-4 ond digit the line relay 46 at the iirst selector E operates in the manner previously described to send two ground impulses to conductor 116. Now, since the second selector wipers are resting on bank contacts of the .irstleveh these ground impulses are transmitted to the connector (Fig. 3) over trunk conductor 124l and thence through the vertical magnet 185 and side switch wiper 205 .to the battery B. The vertical magnet thus receives two impulses and operates in the usual manner to raise the shaft and wipers two steps. The relay 48 ofthe first selector .the calling subscribers.

F energizes as before when the first impulse is sent from the substation and operates to ground the conductor 115. From conductor 115 ground is extended through the second selector F to trunk conductor 1233, thence through the private magnet 188 to battery B. This circuit through the` private magnet 188 remains closed until the last impulse for the digit is received, when the relay 48 dcenergizes and cuts ground from conductor 115. The private magnet 188 is thereupon deenergized and allows the side switch -to pass to second position. When the side switch passes from first to second position battery is disconnected from the verticall magnet 186 by the wiper 205 and the rotary magnet 187 is connected to battery through the side switch wiper 206. Now, when the calling device is operated for the last digit (O) ten ground impulses are transmitted to the trunk conductor 124a by the operation of relay 46 at the selector E. Since the rotary magnet 187 of the connector (Fig. 3) is now connected to battery, the said rotary magnet responds to these ten impulses to rotate the shaft wipers onto the tenth contact of the second bank level, which is the terminal of the desired line. The private magnet 188 operates for the last digit as for the third, if the called line is idle, and releases the side switch to third position. .If the called line is busy, however, the private wiper finds a grounded contact, as previously explained, and closes a holding circuit through the private magnet 188. The side switch is thus locked in second position andthe calling subscriber is given the busy signal. The release of the connector shown in Fig. 3 takes place in the same manner as explained for the connector H.

From the foregoing it will be seen that I provide combined first selectors and repeaters having provisions for feeding battery current Jfor talking purposes to the lines of TheI lines of the called subscribers receive current for talking purposes from the same or a different source, but not through any coils or other devices of the first selectors. The talking current for the called subscribers is fed through the connectors'and does not pass over the trunk ortrunk'siby which calling and called telephonelines are connected together. lli/*hen the call is from one telephone line to another telephone line in the same exchange a second selector F is used, which selector is without line relays, the actuating magnets thereof being directly controlled by the line relays of the first selector. For a local call of this kind it is also true that the connector, which is shown in Fig. 3, is employed, which connector is also without line relays, its actuating' magnets being controlled by the line relays of the first selector. However, when the call is from a telephone line of one exchange to a telephone line of a subexchange, or of a second eX- change, then the connector H, shown in Fig. 2, is employed, which connector has its own individual line relays, such as the relays 68 and 62, the latter being similar to what is ordinarily known as the vertical line relay. The second selector F is, of course, used for both local and long dist-ance calls, such as those just described. Againit will be seen that the line relay or relays of the first selector E serve to repeat calling impulses from two-wire to three-wire line circuits. By this I mean that the original impulses'are transmitted over complete metallic line circuits without the necessity of grounding the line at the calling substation; and that these impulses are then repeated by the relay or relays of the first selector in circuits that do not include the two sides of the trunk line in parallel, inasmuch as these circuits necessarily include the ground at each end of the trunk line. In other words, the original impulses transmitted by the calling sub` scriber are transmitted over circuits including the two sides of the calling telephone line in series, whereas the repeated impulses are -transmitted over ground circuits that each include only one side of the trunk line vto a three-wire circuit in the manner eX- plained.

What I claim as my invention is 1. In a common battery telephone system, subscribers lines, means for establishing a talking circuit between two of said lines, said means including a plurality o f auto matic switches, means for controlling the operation of said switches by a varying number of impulses corresponding to the 'digits of the called number, each switch provided with a propelling mechanism, anactuating magnet for operating said propelling mech anism, circuits including trunk conductors for energizing said magnets. a relay for successively controlling said circuits, means 'in cluding a metallic line circuit for controlling said relay,'and instrumentalities independent of said trunk conductors for supplying talking current to the calling and called lines.

2. In a common battery telephone system, subscribers lines,`means for establishing a talking circuit between two of said lines, said means including an automatic step-by step switch, means for controlling the operationbf said switch by a varying number of impulses corresponding to the dig-its of the called number a magnet having its armature provided with means for directly actuating or propelling said switch, a circuit including a trunk conductor for energizin lsaid magnet, a relay for controlling sai circuit, means including -a metallic line circuit for controllingsaid relay, an automatic switch mechanism allotted to and controlled by said relay, and instrumentalities indeendent of said trunk conductor for supplying talking current to the calling and called lines.

3. In a common battery telephone system, subscribers lines, means for establishing a talking circuit between two of said lines, said means including la plurality of automatic switches, means for controlling the operation offsaid switches by a varying number of `impulses corresponding to the digits of the called number, each switch provided with a propelling mechanism, an actuatingmagnet tor operating said propelling mechanism, circuits including trunk conductors for energizing` said magnets, a relay for succesa sively controlling said circuits, means inclu-ding a metallic line circuit for controlling said relay, an automatic switch mechanism allotted to and controlled by said relay, and instrumentalities independent of said trunk conductors for supplying talking current to the calling and called lines.

4. In a common battery system, subscribers lines, means for establishing a talking circuit between two of said lines, said means including trunks divided into groups, a plurality of automatic trunk-selecting switches, each switch provided with a propelling mechanism, an actuating magnet for operating said propelling mechanism, circuits including trunk conductors for energizing said magnets, a relay for successively controlling said circuits, means including a' metallic line circuit for controlling said relay, an automatic switch mechanism normally connected to and controlled by said relay, said automatic switch mechanism having motion lirst in one plane to select a group and then motion in a plane at right-angles to said other plane to automatically select an idle trunk in the predetermined group. and instru mentalities independent of said trunk con ductors for supplying talking current to the calling and called lines.

5. In a common battery telephone system, subscribers lines, means for establishing a talking circuit between two ot saidlines, said means including an automatic step-bystep switch, means tor controlling the operation ot' said switch by a varying number ot impulses corresponding to the 'digits of the called number a magnet having its armature provided with means for directly actuating or propelling said switch, a circuit including a trunk conductor for energizing said inagnet, a relay for controlling said circuit, means including a metallic line circuit for controlling said relay. means for automatically extending connection to said automatic switch, and instrumentalities independent of said trunk conductor for supplying talking current to the calling and called lines.

6. In a common battery telephone system, subscribers lines, means for establishing a talking circuit between two of said lines, Said means including a plurality of automatic switches, means for controlling the operation of said switches by/a varying number of impulses corresponding to the digits of vthe called number, each switch provided.

with a propelling mechanism, an actuating magnet for operating said propelling mechanism, circuits including trunk conductors for energizing said magnets, a relay for successively controlling said circuits, means including a metallic line circuit for controlling said relay, means for automatically extending connection to said automatic switches, and instrumentalities independent of said trunk conductors for supplying talking current to the calling and 'called lines.

7. In a common battery telephone system, i

subscribers lines, means for establishing a talking circuit between two of said lines, said means including a plurality ol"- automatic switches, means for controlling the operation of said switches by a varying number of impulses corresponding to the digits of the called number, eachl switch pro vided with a propelling mechanism, an actuating magnet for operating said propelling mechanism, circuits including trunk conductors for energizing said magnets, a relay for successively controlling said circuits, mea-ns including a metallic line circuit for controlling said relay, the said energizing cir.

cuits including a ground connection controlled by said relay, and instrumentalities independent of said trunk conductors for supplying talking current to the calling and called lines.

8. In a common battery telephone system, subscribers lines, means tor establishing a talking circuit between two of said lines, said means including an automatic stepby step switch, means for controlling the operaf tion of said switch by a varying number of impulses corresponding to the digits of the called number, a magnet having its..` armature provided with means for directly actu-i.

ating or propelling said switch, a circuit including a trunk conductor for energizing said magnet, a relay for controllingr said` circuit, means including a metallic line circuit tor controlling said relay. an automatic switch mechanism allotted to and controlled by said relay, the said energizing circuit including a ground connection controlled bv said relay, and instrumentalities independ ent of said trunk conductor for supplying talking current to the calling and called lines.

9. In a common battery telephone system, subscribers lines, means for establishing a talking circuit between two of said lines, said means including a plurality of automatic switches, mea-ns for controlling the operation of said switches by a varying number of impulses corresponding to the digits of the called number, each switclr provided witli a propelling mechanism, an actuating magnet for operating said propelling mechanism, circuits including trunk conductors for energizing said magnets, a relay for successively controlling said circuits, means including a metallic line circuit for controlling said relay, an automatic switch mechanism allotted to and controlled by said relay, the said energizing circuits including a ground connection controlled by said relay, and instrumentalities independent of said trunk conductors for supplying talking current to the calling and called ines.

10. In a common battery system, subscribers lines, means for establishing a talking circuit between two of said lines, said means including trunks divided into groups, a plurality ot automatic trunk-selecting switches, each switch provided with a propelling mechanism, an actuating magnet tor operating said propelling mechanism, circuits including trunk conductors for energizing said magnets, a relay for successively controlling said circuits, means including a metallic line' circuit for controlling said relay, an automatic switch mechanism normally connected to and controlled by said relay, said automatic switch mechanism having motion first in one plane to select a group and then motion in a plane at right-angles to said other plane to automatically select an idle trunk in the predetermined group, the said energizing circuits including aground connection controlled by said relay, and instrumentalities independent of said trunk conductors for supplying talking current to the calling and called lines.

11. In a common battery telephone system, subscribers lines, means for establishing a talking circuit between two of said lines, said. means including an automatic step-bystep switch, means for controlling the operation of said switch by a varying number of impulses corresponding to the digits of the called number, a magnet having its armature provided with means forv directly actuating or propelling said switch, a circuit including a trunk conductor for energizing said magnet, a relay for controlling said circuit, means including a metallic line circuit for controlling said relay, means for automatically extending connection to said automatic switch, the said energizing circuit including a ground connection controlled by said relay, and instrumentalities independent of said trunk conductor for supplying talking current to the calling and called lines.

l2. In la common battery telephone sys-v automatic switches, means for controlling the operation of said switches by a .varying number of' impulses corresponding to the digits oi the called number, each switch provided with a propelling mechanism, an actuating niagnet for operating said propelling mechanism, circuits including trunk conductors for energizing said magnets, a relay for successively controlling said circuits, means including a metallic line circuit for controlling said relay, means for automatically extending connection to said auto-- matic switches, the said energizing circuits including a ground connection controlled by said relay, and instrumentalities independent ol' said trunk conductors for supplying talking current to the calling and called lines.

13. In a common battery telephone system, subscribers lines, means for establishing a talking circuit between two of said lines` said means including an automatic step-by-step switch, a magnet having its armature provided with means for directly actuating or propelling said switch, a circuit including a trunk conductor for energizing said magnet, a relay for controlling said circuit, means including a metallic line circuit for controlling said relay, a` pair of voicecurrent trunk conductors between which said relay is permanently bridged, and instrumentalities independent of said iirst-mentioned trunk conductor for supplying talking current to the calling and called lines.

14A. In a common battery telephone system, subscribers lines, means for establishing a talking circuit between two of said lines, said means including a plurality of automatic switches, each switch provided with a propelling mechanism, an actuating magnet for operating said propelling mechanism, circuits including trunk conductors for energizing said circuits, a relay k:tor successively controlling said circuits, means including a metallic line circuit tor controlling said relay, a pair of voice-current trunk conductors between which said relay is permanently bridged, and instrunientalities independent of said first-mentioned -trunk conductors for supplying talking current to the 120 anism, circuits including trunk conductors for energizing said magnets, a relay for successively controlling said circuits, means including a metallic line circuit for controlling said relay, an automatic switch mechanism allotted to and controlled by said relay, a pair of voice-current trunk conductors between which said relay is permanently bridged, and instrumentalities independent of said first-mentioned trunk conductors for supplying talking current to the calling and called lines.

17. In a common battery system, subscribers lines, means for establishing a talking circuit between two of said lines, said means including trunks divided into groups,

an automatic step-by-step switch, a magnet having its armature provided with means for directly actuating or propelling said switch, a circuit including a trunk conductor for energizing said magnet, a relay for controlling said circuit, means including a metallic line circuit for controlling said relay, an automaticswitch mechanism allotted to and controlled by said relay, said automatic switch mechanism having motion first in one plane to select a group and then motion in ^a plane at right-angles to said other plane to automatically select an idle trunk in the predetermined group, a pair of voicecurrent trunk conductors between which said relay is permanently bridged, and instrumentalities independent of said firstmentioned trunk conductor for supplying talking current to the calling and called lines.

18. In a common battery system, subscribers lines, means for establishing a talking circuit between two of said lines, said means including trunks divided into groups, a plurality of automatic switches, each switch provided with a propelling mechanism, an actuating magnet for operating said propelling mechanism, circuits including trunk conductors for energizing said magnets, a relay for successively controlling said circuits, means including a metallic line circuit for controlling said relay, an automatic switch mechanism allotted to and controlled by said relay, said automatic switch mechanism having motion first in one plane to select a group and then motion in a plane at right-angles to said other plane to automatically select an idle trunk in the predetermined group, a pair of voicecurrent trunk conductors between which said relay is permanently bridged, and instrumentalities independent of said first-mentioned trunk conductors for supplying talking current to the callingand called lines.

19. In a common battery telephone system, subscribers lines, means for establishing a talking circuit between two of said lines, said means including an automatic step-bystep switch, a magnet having its armature provided with means for directly actuating or propelling said switch,a circuit inclu-ding aitrunk conductorfor energizing said magnet, a relay for controlling said circuit, means including a metallic line circuit for controlling said relay, means for automatically extending connection to said automatic switch, a pair of voice-current trunk conductors between which said relay is permanently bridged, and instrumentalities independent of' said first-mentioned trunk conductor for supplying ltalking current to the calling and called lines.

20. In a common battery telephone system, subscribers lines, means for establishing a talking circuit between two of said lines, said means including a plurality of automatic switches, each switch provided with a propelling mechanism, an actuating magnet for 4operating said propelling mechanism, circuits including trunk conductors for energizing said magnets, a relay for successively controlling said circuits, means including a metallic line circuit for controlling said relay, means for automatically extending connection to said automatick switches, a pairiof voice-current trunk conductors between which said relay is permanently bridged, and instrumentalities independent of said first-mentioned trunk conductors for supplying talking current to the calling and called lines.

21. In a ltelephone system, subscribers lines, means for establishing a talking circuit between twoof said lines, said means including a first selector common to a plurality of said lines provided with a line relay normally connected thereto, means for controlling the operation of said switch by a varying number of impulses corresponding to the digits of the called number, said impulses delivered over a circuit including the two sides of a calling line in series, a trunk line adapted to be seized by said first selector, an automatic switch having a progressively movable element, a magnet having an armature for driving said element, a circuit for said magnet extending over said trunk line and controlled by said relay after the first selector has seized Aeo said trunk, and means independent of said selector for supplying talking current to any substation called through the medium thereof.

22. In a telephone system, subscribers lines, means for establishing a talking circuit between two ot' said lines, said means including an automatic switch common to a plurality of said lines and provided with a line relay, means for controlling the operation of said Aswitch by a varying number of impulses corresponding to the digits of the called number, a trunk line adapted to be seized by said switch, a circuit for controlling said relay including the two sides of a calling line in series, a switch having a progressively movable element, a magnet having an armature for driving said element, a circuit for said magnet-extending over said trunk line and controlled by said relay, and means independent of said automatic switch for supplying talking current to any substation called through the medium thereof.

23. In a telephone station, subscribers lines, means for establishing a talking circuit between two of said lines, said means including a first selector common to a plurality of said lines and provided with a line relay normally connected thereto, a circuit including the two sides of said talking circuit in series for controlling said relay, means for controlling the operation of said switch by a varying number of impulses corresponding to the digits of the called number, a trunk line adapted to be seized by said first selector, an automatic switch having wipers, a magnet having an armature for driving said wipers, a circuit for said lmagnet extending over said trunk line and controlled by said line relay after the first selector has seized 'said trunk line, suitable means for extending a connection to said first selector, and means independent of said first selector for supplying current to any substation called through the mediumthereof.

24. In a telephone system, subscribers lines, means for establishing a talking circuit between two of said lines, said means including an automatic switch commonpto a plurality of said lines and provided with a line relay, means for controlling the operation ot' said switch by a varying number of impulses corresponding to the digits of the called number, a circuit including the two sides of a portion of said talking circuit 1n series for controlling said relay, a trunk llne adapted to bue seized by said switch, another switch having wipers, a magnet for driving said wipers, a circuit for said magnet eX- tending over said trunk line and controlled by said relay, a selector also controllable by said relay, and operative for switching 1n accordance with a digit of the called number, and means independent of said automatic switch for supplying talking current to any substation called through the medium thereof. Y

25. 'In a telephone exchange trunking system, a talking circuit, an automatic step-bystep switch, means for controlling the operation oi' said switch by a varying number of impulses corresponding to the digits of the called number, a magnet having its armature provided withy means for directly actuating or propelling said switch, a circuit including a trunk conductor for energizing said magnet, a relay forcontrolling said circuit, means including the two sides or" said talking circuit in series for controlling said relay, a connector havingy a line relay controlled by said relay, and an actuatingmagnet controlled by said line relay.

26. In a telephone exchange trunking system, a talking circuit, a plurality of automatic switches, means for controlling the operation of said switches by a varying number of impulses corresponding to the digits of the called number, each switch provided with a propelling mechanism, an actuating magnet for operating said propelling mechanism, circuits including trunk conductors for energizing said magnets, a relay for successively controlling said circuits, means including the two sides of said talking circuit in series for controlling said relay, a connector rhaving a line relay controlled by said relay, and an actuating magnet controlled by said line relay. 27. In a telephone exchange trunking system, the combination of a talking circuit, an

automatic step-by-step switch, means for controlling the operation of said switch by a varying number of impulses corresponding to the digits of the called number, a magnet having its armature provided with means for directly actuating or propelling said switch, a circuit including a trunk conductor for energizing said magnet, a relay for controlling said circuit, means including the two sides of said talking circuit in series for controlling said relay, an automatic switch mechanism allotted to and controlled by said relay, a connector having a 'line relay controlled by said relay, and an actuating magnet controlled by said line relay.

28. In a telephone exchange trunking system, the combination of a talking circuit a plurality of automatic switches, means 0r controlling the operation of said switches by a varying number of impulses correspondin to the digits of the called number, eacii switch provided with a propelling mechanism, an actuating magnet for operating said propelling mechanism, circuits including trunk conductors for energizing said magnets, a relay for successively controlling said circuits, means including the two sides of said talking circuit in series for controlling said relay, an automatic switch mechamatic step-by-step trunk-selecting switch, a

magnet having its armature provided with means' for directly actuating or propelling said switch, a circuit including a trunk conductor for energizing said magnet, a relay for controlling said circuit, means including the two sides of said talking circuit in series for controlling said relay, an automatic i switch mechanism normally connected to and controlled by said relay, said automatic switch mechanism having motion first in one plane to select a group and then motion in a plane at right-angles to said other plane to automatically select an idle trunk in the predetermined group, a connector having a line relay controlled by said relay,r and an actuating magnet controlled by said line relay. 30. In a telephone exchange trunking system having trunks divided into groups, the combination of a talking circuit, a plurality of automatic trunk-selecting switches, each switch provided with a propelling mechanism, an actuating magnet for operating said propelling mechanism, circuits including trunk conductors forV energizing said magnets, a relay foi` successively controlling said circuits, means including the two sides of said talking circuit in series for controlling said relay, an automatic switch mechanism normally connected to and controlled by said relay, said automatic switch mechanism having motion first in one plane to select a group and then motion in a plane at right-angles to said other plane to automatically select an idle trunk in the predetermined group, a connector having a line relay controlled by said relay, and an actuating magnet controlled by said line relay.

31. In a telephone exchange trunking system, the combination of a talking circuit, an automatic step-by-step switch, means for controlling the operation' of said switch lby a varying number of impulses corresponding to the digits of the called number, a magnet having its armature provided with means for directly actuating or propelling said switch, a circuit including a trunk conductor for energizing said magnet, a relay for controlling said circuit, means including the two sides of said talking circuit in series for controlling said relay, means for automatically extending connection to said automatic switch, a connector having a line relay controlled by said relay, and an actuating magnet controlled by said line relay.

32. In a telephone exchange trunking system, the combination of a talking circuit, a plurality of automatic switches, each switch provided with a propelling mechanism, an actuating magnet for operating and propelling mechanism, circuits including trunk conductors for energizing said magnets, a relay for successively controlling said circuits, means including the two sides of said talking circuit in series for controlling said relay, means for automatically extending connection to said automatic switches, a connector having a line relay controlled by said relay, an actuating magnet controlled by said line relay, and means in the connector for feeding talking current to any substation called through the medium thereof.

33. In a telephone exchange trunking system, an automatic step-by-step switch, a -magnet having its armature provided with means for directly actuating or propelling said switch, a circuit including a trunk conductor for energizing said magnet, a relay for controlling said circuit, means includin a metallic line circuit for controlling Said relay, means at the central station for supplying talking current over said metallic circuit, a connector having a line relay controlled by said relay, an actuating magnet controlled by said line relay,'and means in the connector for feeding talking current to any substation called through the medium thereof.

34. In a telephone exchange trunking system, a plurality of automatic switches, each switch provided with a propelling mechanism, an actuating magnet for operating said propelling mechanism, circuits including trunk conductors for energizing said magnets, a relay for successively controlling said circuits, means including a metallic line circuit for controlling said relay, means at the central station for supplying talking current over said metallic circuit, a connector having a line relay controlled by said rela an actuating magnet controlled by sai line relay, and means in the connector for feeding talking current to any substation called through the medium thereofy 35. In a telephone exchange trunking system, the combination of an automatic step-` by-step switch, a magnet having its armature provided with means for directly actuating or propelling said switch, a circuit including a trunk conductor for energizing said magnet, a relay for controlling said circuit, means including a metallic line circuit for controlling said relay, an automatic switch mechanism allotted to and controlled by said relay, means atthe central station for supplying talking current over said metallic circuit, a connector having a line relay controlled bysaid relay, an actuating magnet rcontrolled 'by said line relay,E and means in the connector for feeding talking current to any substationcalled through the medium thereof.

36. In a telephone exchange trunking system, the combination of a plurality of automatic switches, each switch provided with a propelling mechanism, an actuating magnet for operating said propelling mechanism, circuits including trunk conductors for energizing said magnets, a relay for successively controlling said circuits, means including a metallic line circuit for controlling said relay, an automatic switch mechanism alotted to and controlled by said relay, means at the central station for supplying talking current over said metallic circuit, a

connector having a line relay controlled by said relay, an actuating magnet controlled by said line relay, and means in the connector for feeding talking current to any substation called lthrough the medium thereof.

37. In a telephone exchange trunking system having trunks divided into groups, the combination of'an automatic step-by-step switch, a magnet having its armature provided with means for directly actuating or propelling said switch, a circuit including a trunk conductor for energizing said magnet, a relay for controlling` said circuit, means including a metahic line circuit for controlling said relay, an automatic switch mechanism allotted to and controlled by said relay, said automatic switch mechanism having motion first in one plane to select a group and then motion in a plane at right` angles to said other plane to automatically select an idle trunk in the predetermined group, means at the central station for supplying talking current over said metallic circuit, a connector having a line relay controlled by said relay, an actuating magnet controlled by said line relay, and means in the connector for feeding talking current to any substation called through the medium thereof.

38. In a telephone exchange trunking system having trunks divided into groups, the combination' of a plurality of automatic switches, each switch provided with a propelling mechanism, an actuating magnet for operating said propelling mechanism, circuits including trunk conductors for energizing said magnets, a relay for successively controlling said circuits, means including a metallic line circuit for controlling said relay, an automatic switch mechanism allotted to and controlled by said relay, said automatic switch mechanism having motion first in one plane to select a group and then motion in a plane at right-angles to said other plane to automatically select an ide trunk in the preditermined group, means at the central station for supplying ytalking current over said metallic circuit,

a connector having a line relay controlled by said relay, an actuating magnet controlled by said line relay, and means in the connector for feeding talking current to any substation called through the medium thereof.

39. In a telephone exchange trunking system, the combination of an automatic stepby-step switch, a magnet having its armature provided with means for directly actuatingr or propelling said switch, a circuit including a trunk conductor for energizing said magnet, a relay for controlling said circuit, means including a metallic line circuit for controlling said relay, means for automatically extending connection to said automatic switch, means at the central station for supplying talking current over said metallic circuit, a connector having a line relay controlled bysai-d relay, an actuating niagnet controlled by said line relay, and means in the connector for feeding talking current to any substation called through the medium thereof.

40. In a telephone exchange trunking system, the combination of a plurality of automatic switches, each switch provided with a propelling mechanism, an actuating magnet for operating said propelling mechanism, circuits including trunk conductors for energizing said magnets, a relay for successively controlling said circuits, means incuding a metallic line circuit for controlling said relay, means for automatically extending connection to said automatic switches,

means at the central station for supplying talking current over said metallic circuit, a connector having a line relay controlled by said relay, an actuating magnet controlled by said line relay, and means in the connector for feeding talking current to any substation called through the medium thereof.

41. In a telephone exchange trunking system, an automatic step-by-stcp trunk-selecting switch, a magnet having its armature provided with means for directly actuating or propelling said switch, a circuit including a trunk conductor for energizing said magnet, a relay for controlling said circuit, means including a metallic line circuit for controlling said relay, and a connector provided with a line relay permanently connected with the line circuit thereof`l the said energizing circuit including a ground connection controlled by said first-mentioned relay.

42. In a telephone exchange trunking system, a plurality of automatic trunk-selecting switches, each switch provided with a.

propelling mechanism, an actuating magneti for operating said propelling mechanism, circuits including trunk conductors for energizing said magnets, a relay for successively controlling said circuitsdneans including a metallic line circuit for controlling Laid relay, and a connector provided with a line relay permanently connected with the line circuit thereof, the said energizing circuits including a groundl connection controlled by said first-mentioned relay.

43. In a telephone exchange trunliing system, the combination of an automatic stepby-step trunk-selecting switch, a magnet having its armature providedl with means for directly actuating or propelling said switch, a circuit including a trunk conductor 'for energizing said magnet, a relay for controlling said circuit, means including a metallic line circuit for c'ontrolling said relay, an automatic switch mechanism allotted to and controlled by said relay, and a connector provided with a line relay permanently connected with the line circuit thereof, the said energizing circuit including a ground connection controlled by said relay.

44. In a telephone exchange trunking system, the combination of a plurality of 'automatic trunk-selecting switches, each switch provided with a propelling mechanism, an actuating magnet for operating said propelling mechanism, circuits including trunk conductors for energizing said magnets, a relay for successively controlling said circuits, means including a metallic line circuit for controlling said relay, an automatic switch mechanism allotted to and controlled by said relay, anda connector provided with a line relay permanently connected with the line circuit thereof, the said energizing circuits including a ground connection controlled b said first-mentioned relay.

45. In a telep one exchange trunking system having trunks divided into groups, the combination of an automatic step-by-step trunk-selecting switch, a magnet having its armature'provided with means for directly actuating or propelling said switch, a circuit including a trunk conductor for energizing said magnet, a relay for controlling said circuit, means including a metallic line circuit for controlling said relay, an automatic switch mechanism allotted to and controlled by said relay, said automatic switch mechanism having moti'on first in Vone plane to select a group and then motion in a plane 'at right-angles to said other plane to automatically select an idle trunk in the predetermined group. and a connector provided with a line relay permanently connected with the line circuit thereof, the said energizing circuit including a ground connection controlled by said first-mentioned relay. 46. In a-telephone exchange trunking system having trunks divided into groups, the combination of a plurality of automatic trunk-selecting switches, each switch provided with a propelling mechanism, an actuating magnet for operating said propelling mechanism, circuits including trunk conductors for energizing said magnets, a relay for successively controlling said circuits, means including a metallic line circuit for controlling said relay, an automatic switch mechanism allotted to and controlled by said relay,-said automatic switch mechanism having motion iirst in one plane to select a group and then motion in a plane at right-angles to said other plane to automatically select an idle trunk in the predetermined group, and a connector provided with a line relay permanently connected with the line circuit thereof, the said energizing circuits including a ground connection controlled by said first-mentioned relay.

47. In a telephone exchange trunlring system, the combination of an automatic stepby-step trunk-selecting switch, a magnet' .having its armature provided with means Jfor directly actuating or propelling said switch, a. circuit includinga trunk conductor for energizing said magnet, a relay for controlling said circuit, means including a metallic line circuit for controlling said relay, means or automatically extending connection to said automatic switch, and a connector provided with a line relay permanently connected with the line circuit thereof, the said energizing circuit including a ground connection controlled by said irstmentioned relay.

48. In a telephone exchange trunlring system, the combination of a plurality of automatic trunk-selecting switches, each switch provid'ed with a propelling mechanism, an actuating magnet for operating said propelling mechanism, circuits' including trunk conductors for energizing said magnets, a relay for successively controlling said circuits, means including a metallic line circuit for controlling said relay, means for automatically extending connection to said automatic switches, Vand a connector provided with a line rel-ay permanently connected with the line circuit thereof, the' said energizing circuits including a ground connection controlled by said irst-mentioned relay.

49. In a telephone exchange trunlring system, an automatic step-by-step switch, a

magnet having its armature providedwith means for directly actuating or propellingsaid switch, a circuit including a trunk conductor for energizing said magnet, a relay for controlling said circuit, means including la metallic line circuit orcontrolling said relay, a pair of voice-current trunk conducy tors between which said relay is permanently bridged, and a vertical and rotary motion connector provided with a line relay responsive to said relay, which line relay controls the'vertical and rotary motion of said connector.

50. In a telephone exchange trunlring system, a plurality of automatic switches, each switch provided with a propelling mechanism, an actuating magnet for operating said propelling mechanism, circuits includ- -ing trunk conductors for energizing said magnets, a relay lor sucessively controlling said circuits, means including a metallic line circuit for controlling said relay, a pair ot voice-current trunk conductors between which said relay is permanently bridged, and a vertical and rotary motion connector provided with a line relay responsive to said relay, which line relay controls the vertical and rotary motion of said connector.

51. In a telephone exchange trunliing system, the combination of an automatic stepby-step switch, a magnet having its armature provided with means for directly actuating or propelling said switch, a circuit including a trunk conductor for energizing said magnet, a relay for controlling said circuit, means including a metallic line circuit for controlling said relay, an automatic switch mechanism allotted to and controlled by said relay, a pair of voice-current trunk conductors between which said relay is permanently bridged, and a vertical and rotary motion connector provided with a line relay responsive to said relay, which line relay controls the vertical and rotary motion of said connector.

52. In a telephone exchange trunking system, the combination of a plurality of automatic switches, each switch provided with a propelling mechanism, an actuating magnet for Ioperating said propelling mechanism, circuits including trunk conductors for energizing said magnets, a relay for successively controlling said circuits, means including a metallic line circuit for controlling said relay, an automatic switch mechanism allotted to and controlled by said relay, a pair of voice-current trunk conductors between which said relay is permanently bridged, and a vertical and rotary mo-` tion connector provided with a line relay responsive to said relay, which line relay controls the vertical and rotary motion of said connector. c

53. In a telephone exchange trunking system having trunks divided into groups, the combination of`an automatic step-by-stepswitch,a magnet having its armature provided with means for directly actuating or propelling said switch, a circuit including a trunk conductor for energizing said magnet, a relay for controlling said circuit, means including a metallic line circuit for cgntrollingl said relay, an automatic switch mechanism allotted to and controlled by said relay, said automatic switch mechanism having motion first in one plane to select a group and then motion in a plane at rightangles to said other plane to automatically select an idle trunk in the predetermined group, a pair of voice-current trunk conductors between which said relay is permanentlv bridged. and a vertical and rotaryv motion connector provided with a line relay responsive'to said relay, which line relay controls the vertical and rotary motion of said connector.

54. In a telephone exchange trunking system having trunks divided into groups, the combination of a plurality of automatic switches, each switch provided with a propelling mechanism, an actuating magnet for operating said propelling mechanism, circuitsincluding trunk conductors for energizing said magnets, a relay for successively controlling said circuits, means including a metallic line circuit for controlling said relay, an automatic switch mechanism allotted to and controlled by said relay, said automatic switch mechanism having motion irst in one plane to select a group and then motion in a plane at right-angles to said other plane to automatically select an idle trunk in the predetermined group, a pair of voice-current trunk conductors between which said relay is permanently bridged,

and a vertical and rotary motion connector provided with a line relay responsive to said relay, which line relay controls the vertical and rotary motion of said connector.

55. In a telephone exchange trunking system, the combination of an automatic stepbay-step switch, a magnet having its armature provided with means for directly actuating or propelling said switch, a circuit including a trunk conductor for energizing said magnet, a relay for controlling said circuit, means including a metallic line circuit for controlling said relay, means for automatically extending connection to said automatic switch, a pair of voice-current trunk conductors between which said relay is permanently bridged, and a Vertical and rotary motion connector provided with a line relay responsive to said relay, which line relay controls the vertical and rotary motion of said connector.

56. In a telephone exchange trunking system, the combination of a plurality of automatic switches, each switch provided with a propelling mechanism, an actuating magnet for operating said propelling mechanism, circuits including trunk conductors for energizing said magnets, a relay for successively controlling said circuits, means including a metallic line circuit for controlling said relay, means for automatically extending connection to said automatic switches, a pair of voice-current trunk conductors between whi'ch said relay is permanently bridged, and a vertical and rotary -motion connector provided with a line relay responsive to said relay, which line relay controls the vertical and rotary motion of said connector.

57. In a telephone exchange repeater system, subscribers lines, a plurality of trunks, a plurality of automatic switches., means for cont-rolling the operation of said switches by a varyingl number of impulses corresponding to t e digit-s of the called number', each switch provided with a propelling mechanism, an actuating magnet for operating said pr-opelling mechanism, groundA circuits including only one side of said trunks for energizing said magnets, a relay for successively controlling said circuits, and means including the two sides of a calling line in series for controlling said relay. l

58. ln a telephone exchange repeater system, subscribers lines, the combination oi' a plurality of tiunks, a plurality of automatic switches, means for controlling the operation of said switches by a varying number of impulses corresponding to the digits ot the called number, with a propelling mechanism, an actuating magnet for operating said propelling mechanism, ground circuits including only one side of said trunks for energizing said mag nets, a relay for successively cont-rolling said circuits, means including the two sides of the calling line in series for controlling said relay, and an automatic switch mechap nism allotted to and controlled by said relay.

till

59. In a telephone exchange repeater sys-V tem having trunks divided into groups, subscribers lines, the combination of a plurality of automatic trunk-selecting switches, each switch provided with a propelling mechanism, an actuating magnet for operating said propelling mechanism, ground circuits iiicluding only one side of said trunks Jfor energizing said magnets, a relay for successively controlling said' circuits, means including the two sides of a calling line in series for controlling said relay, and an automatic switch mechanism normally connected to and controlled by said relay, said automatic switch mechanism having motion tirst in one plane to select a group and then motion in a plane at right-angles to said other plane to automatically select an idle trunk in the predetermined group. y

60. In a. telephone exchange repeater system. subscribers lines, the combination of a plurality oi trunks, a plurality of automatic switches, means for controlling the operation oi said switches by a varying number of impulses corresponding to the digits o t the called number, each switch `provided with a propelling mechanism, an actuating magnet for operating said propelling mechanism, ground circuits including only one side oi' said trunks Jfor energizing said magnets, a relay for successively controlling said circuits, means including' the two sides of a calling line in series for controlling said relay, and means for automatically extending connection to said automatic switches.

G1. ln a telephone exchange repeater system, a trunk, an automatic step-by-step switch. means for controlling the operation ot' said switch by'a varying number of imeach switch provided pulses corresponding to the digits of the called number, a magnet having its armature provided with means for directly actuating or propelling said switch, a ground circuit including only one side of said trunk for energizing said magnet, a relay for controlling said circuit, means including a metallic line circuit for controlling said relay, and means at the central station for supplying talking current over said metallic circuit.

62. In a telephone exchange repeater system, the combination of a trunk, an automatic step-by-step switch, means for controlling the operation of said switch by a varying number to the digits of the called number, a magnet having its armature provided with means for directly actuating or propelling said switch, a ground circuit including only one side of said trunk for energizing said magnet, a relay for controlling said circuit, means including a metallic line circuit for controlling said relay, mechanism allotted to and controlled by said relay, and means at the central station Jfor supplying talking current over said metallic circuit. f

In a telephone exchange repeater system, the combination of a plurality of trunks, a plurality of automatic switches,

means for controlling the o eration of said switches by a varying numlgi corresponding to the digits of the called number, each switch provided with a propelling-mechanism, an actuating magnet for operating said propelling mechanism, ground circuits including only one side of said trunks for energizing said magnets, a relay for successively controlling said circuits, means including a metallic line circuit for controlling said relay, an automatic switch mechanism allotted to and controlled by said relay, and means at the central station for vsupplying talking current over said metallic circuits 64. In a telephone exchange repeater syslem having trunks divided, into groups, the combination of a plurality of automatic trunk-selecting switches, ,each switqch provided with a propelling mechanism, an actuating magnet for operating said propelling mechanism, ground circuits including only one side of said trunks for energizing said magnets, a relay for successively controlling said circuits, means including a metallic line circuit for controlling said relay, an automatic switch mechanism normally connected to and controlled by said relay, said automatic switch mechanism having motion first in one plane to select a group and then motion in a plane at right-angles to said other plane to automatically select an idle trunk in Vthe predetermined group, and means at the central station for supplying talking current over said met-allie circuit.

of impulses correspondingl an automatic switch er of impulses 

